TESTING SIGNIFICANCE OF MULTI-DESTINATION AND MULTI-PURPOSE TRIP EFFECTS IN A TRAVEL COST METHOD DEMAND MODEL FOR WHALE WATCHING TRIPS

Inclusion of multi-destination and multi-purpose visitors has an appreciable influence on a standard count data travel cost model derived estimate of willingness to pay but the differences are not statistically significant. We adapt a more general travel cost model (TCM) of Parsons and Wilson (1997) that allows for inclusion of multi-destination visitors as incidental demand to allow estimation of an unbiased measure of single and multi-destination willingness to pat for whale viewing using a single pooled equation. The primary purpose trip values from the standard TCM and simple generalized TCM model are identical at $43 per person per day and neither are significantly different from the$50 day value from a generalized model that distinguishes between joint and incidental trips. The general models avoid underestimation of total recreation site benefits that would result from omitting the consumer surplus of multi-destination visitors.Resource /Energy Economics and Policy,

ケイサンキ シミュレーション ニヨル FCC キンゾク ノ ハジキ ダシ エネルギー ノ ヒョウカ

FCC金属のはじき出しエネルギーを計算するために, 時間発展的カスケードシミュレーション・コードDYACOCTを用いて, 低エネルギーの1次はじき出しに対する平均はじき出し数を5種類のFCC金属(Al, Ni, Cu, Ag, Au)について計算した。また, シミュレーションに用いる原子間ポテンシャルがシミュレーション結果に与える影響を調べるために, 各金属に対してそれぞれ3種類の原子間ポテンシャル(Moliereポテンシャル, Kr-Cポテンシャル, AMLJポテンシャル)を用いて同様の計算を行なった。そして, はじき出し損傷関数の表式として, 2つの対照的なモデル(Kinchin-Peaseモデルと連続確率モデルを考え, これらを用いてシミュレーション結果からはじき出しエネルギーを計算した。その結果, シミュレーション結果は連続確率モデルに一致することが分かった。また, 計算機シミュレーションによって得られたはじき出しエネルギーは, 実験値と比較すると, 原子番号が比較的小さい金属(Al, Ni, Cu)に対してはMoliereポテンシャルとKr-Cポテンシャルが比較的よく合い, 原子番号が比較的大きい金属(Ag, Au)に対してはAMLJポテンシャルが比較的よく合うことが分かった。In order to investigate displacement energies of FCC (face-centered cubic) metals, the average number of displaced atoms due to low energy PKA (primary knock-on atom) for five FCC metals (Al, Ni, Cu, Ag, Au) have been calculated, using the time-evolution Monte Carlo simulation code DYACOCT. Two displacement models of the Kinchin-Pease model and the continuous displacement probability model have been considered as the displacement damage function, and the displacement energies have been estimated from the results of DYACOCT simulations

FDCCS16 molecular simulation of the thermophysical properties and phase behaviour of impure CO2 relevant to CCS

Impurities from the CCS chain can greatly influence the physical properties of CO2. This has important design, safety and cost implications for the compression, transport and storage of CO2. There is an urgent need to understand and predict the properties of impure CO2 to assist with CCS implementation. However, CCS presents demanding modelling requirements. A suitable model must both accurately and robustly predict CO2 phase behaviour over a wide range of temperature and pressure, and maintain that predictive power for CO2 mixtures with numerous, mutually interacting chemical species. A promising technique to address this task is molecular simulation. It offers a molecular approach, with foundations in firmly established physical principles, along with the potential to predict the wide range of physical properties required for CCS. The quality of predictions from molecular simulation depends on accurate force-fields to de- scribe the interactions between CO2 and other molecules. Unfortunately, there is currently no universally applicable method to obtain force-fields suitable for molecular simulation. In this paper we present two methods of obtaining force-fields: the first being semi-empirical and the second using ab-initio quantum-chemical calculations. In the first approach we optimise the impurity force-field against measurements of the phase and pressure-volume behaviour of CO2 binary mixtures with N2, O2, Ar and H2. A gradient-free optimiser allows us to use the simulation itself as the underlying model. This leads to accurate and robust predictions under conditions relevant to CCS. In the second approach we use quantum-chemical calculations to produce ab-initio evaluations of the interactions between CO2 and relevant impurities, taking N2 as an exemplar. We use a modest number of these calculations to train a machine-learning algorithm, known as a Gaussian process, to describe these data. The resulting model is then able to accurately predict a much broader set of ab-initio force-field calculations at comparatively low numerical cost. Although our method is not yet ready to be implemented in a molecular simulation, we outline the necessary steps here. Such simulations have the potential to deliver first-principles simulation of the thermodynamic properties of impure CO2, without fitting to experimental data

Thermodynamic Models for Vapor-Liquid Equilibria of Nitrogen+Oxygen+Carbon Dioxide at Low Temperatures

For the design and optimization of CO2 recovery from alcoholic fermentation processes by distillation, models for vapor-liquid equilibria (VLE) are needed. Two such thermodynamic models, the Peng-Robinson equation of state (EOS) and a model based on Henry's law constants, are proposed for the ternary mixture N2+O2+CO2. Pure substance parameters of the Peng-Robinson EOS are taken from the literature, whereas the binary parameters of the Van der Waals one-fluid mixing rule are adjusted to experimental binary VLE data. The Peng-Robinson EOS describes both binary and ternary experimental data well, except at high pressures approaching the critical region. A molecular model is validated by simulation using binary and ternary experimental VLE data. On the basis of this model, the Henry's law constants of N2 and O2 in CO2 are predicted by molecular simulation. An easy-to-use thermodynamic model, based on those Henry's law constants, is developed to reliably describe the VLE in the CO2-rich region

Heating Characteristics of Open Steam and Reboiler

蒸留塔の水蒸気加熱とリボイラー加熱の両者の場合における省エネルギー特性を比較検討した。計算手法として Ponchon-Savarit 法を用いた。原料組成, 塔頂組成, 還流比, 塔底加熱量および全段数が等しい条件で塔底液組成と理論段数を比較する場合と, 原料組成, 塔頂組成, 還流比, 塔底組成および全段数が等しい条件で塔底加熱量を比較検討した。その結果, 塔底液が水以外の成分をかなり含んでいる場合は, 水蒸気加熱方式がリボイラー加熱方式よりもかなりの省エネルギー効果があることが明らかになった。The heat consumption of distillation column is considered for both the open steam and reboiler systems. The Ponchon-Savarit method is used for calculations. Cases (A), (B) in Fig. 1 show the calculated results of the bottoms product composition and the theoretical number of plates when feed composition, distillate composition, reflux ratio, heat consumption, and the total number of plates are the same. Cases (A), (C) in Fig. 1 show the calculated results of heat consumption when feed composition, distillate composition, reflux ratio, bottoms product composition, and the total number of plates are the same. The enthalpy-composition diagram used is shown in Fig. 2. The calculated results are summarized in Table 1. Comparing the results of cases (A), (B) in Fig. 1. it is found that the open steam method requires much more theoretical number of plates, but the ethanol content in the bottoms product becomes smaller. Comparing the results of cases (A), (C) in Fig. 1, it is found also that less heat is required by heating with open steam than with a reboiler. This heat saving effect becomes greater as the ethanol content in the bottoms product becomes larger

Characteristics of Azeotropic Distillation Column

ベンゼン, エタノール, 水系に対する共沸蒸留計算を緩和法を用いて行い, 種々の操作条件に対して分離数および熱力学的効率の両面から最適操作条件を検討した。気液モル流量比に関しては第1塔は1.3以下, 第2塔は1.2以下が望ましい。また塔内圧力が上昇すると, エタノールと水の分離が悪くなり, 分離数および熱力学的効率が低下する。さらにベンゼン相と水相の分離を良くするために, デカンターに水を供給した場合, エタノールと水の分離は良くなるが, リボイラー部での必要熱量が増加すること等の新しい知見を得た。The relaxation method was used for azeotropic distillation calculations. For the Benzene-Ethanol-Water system, various operating conditions were examined by use of thermodynamic efficiency and separation number. For vapor-liquid calculations NRTL Eq. was used, and Eq. (3) was used for separation number calculations. Eqs. (4), (5), (6) were used for thermodynamic efficiency calculations. A schematic drawing of azeotropic distillation column is shown in Fig. 1. It was found from Figs. 3, 4, 5 that the ratio of liquid to vapor flow rate for the first column should be less than 1.3. From Figs. 6, 7, 8, it was also found that the ratio of liquid to vapor flow rate for the second column should be less than 1.2. Fig. 9 shows that both the thermodynamic efficiency and separation number were maximized when the temperature of the feed was in the boiling condition. The maximum thermodynamic efficiency was about 0.07. Figs. 10, 11, indicated that as the pressure of the column decreased, the separation of ethanol and water improved. Fig. 11, showed that as the pressure increased, the thermodynamic efficiency decreased. Fig. 12 shows the relation between mole fraction of bottom liquid and water feed rate to the decanter. It indicated that as the water feed rate to the decanter increased, the separation of bottom liquid in the second column improved. But from Fig. 13, it was observed that the greater the water feed rate to the decanter was the greater the reboiler duty